The Lowering of Water Activity by Order of Mixing in Concentrated Solutions

1975 ◽  
pp. 613-626 ◽  
Author(s):  
D.P. BONE ◽  
E.L. SHANNON ◽  
K.D. ROSS
Keyword(s):  
Water Activity ◽  
Concentrated Solutions

Vapour pressures of CaCl2–NaCl–H2O and MgCl2–NaCl–H2O at 25 °C. Prediction of the water activity of supersaturated NaCl solutions

1978 ◽  
Vol 56 (14) ◽  
pp. 1853-1855 ◽  
Author(s):  
Doan Thi An ◽  
Tjoon Tow Teng ◽  
James Malcolm Sangster
Keyword(s):  
Water Activity ◽  
Static Method ◽  
Polynomial Form ◽  
Concentrated Solutions

Vapour pressures of concentrated solutions (up to I = 14) of the Systems CaCl2 + NaCl + H2O and MgCl2 + NaCl + H2O have been measured at 25 °C by the static method. By means of reverse application of the Reilly–Wood–Robinson and Zdanovskii–Stokes–Robinson equations to these data, water activities of supersaturated NaCl solutions up to ∼15 m have been deduced, and are represented in polynomial form.

Solvation properties in iso-acidic media involving phosphoric acid

1988 ◽  
Vol 66 (9) ◽  
pp. 2422-2427 ◽  
Author(s):  
C. Louis ◽  
A. Bebba ◽  
J. Bessière
Keyword(s):  
Carbon Tetrachloride ◽  
Phosphoric Acid ◽  
Water Activity ◽  
Ionic Species ◽  
Concentrated Solutions ◽  
Acidic Media ◽  
Acidic Solutions ◽  
Mineral Acids ◽  
Acidity Level ◽  
Silver Extraction

Concentrated solutions of mineral acids (phosphoric, hydrochloric, perchloric, sulfuric) are characterized, for an equal value of their water activity, by an equal R0(H) acidity level (iso-acidic solutions). By mixing them, we prepare what we call iso-acidic mixtures which keep the same acidity level as the constitutive solutions whatever the proportions; their redox and solvating properties depend both on the nature and on the ratio of the constitutive solutions. Reactivity variations for ionic species: Cl−, Br−,I−, diethyldithiophosphate (LET−), Si(W3Ol0)44−, Si(W3O10)45−, Cu2+, Cu+, Pb2+, Sn2+, Cd2+, Zn2+, Ag+, Fe3+, Fe2+, UO22+, U4+ in the iso-acidic mixtures are characterized by their ƒ solvation-transfer activity coefficients. Relations between ƒ coefficient values and complexation properties are established and it is shown that phosphoric acid has comparatively weak solvating properties toward most species. The possibility for anticipating reaction changes with the iso-acidic mixture composition by using the ƒ coefficients is demonstrated in the case of cadmium ionic flotation with diethyldithiophosphate and silver extraction with dithizone in carbon tetrachloride.

Acidity level in concentrated mineral acid mixtures. Iso-acidic media

1987 ◽  
Vol 65 (6) ◽  
pp. 1353-1355 ◽  
Author(s):  
C. Louis ◽  
A. Bebba ◽  
J. Bessiere
Keyword(s):  
Water Activity ◽  
Mineral Acid ◽  
Acidity Function ◽  
Concentrated Solutions ◽  
Acidic Media ◽  
Comparison System ◽  
Acidic Solutions ◽  
Complexing Properties ◽  
The Relationship ◽  
Acidity Level

Assuming the relationship between the R0(H) acidity function and the water activity in mineral acid concentrated solutions, iso-acidic solutions are prepared by mixing in all proportion two or three of the acids: H3PO4, HCl, HClO4, H2SO4, H2SiF6. These solutions are characterized by an equal R0(H) acidity level and different redox and complexing properties. Their R0(H) acidity level is determined from potential measurements involving o-chloranil as an H+ indicating system and ferricinium/ferrocene as a comparison system.

scholarly journals Evaluation of Norrish’s Equation for Correlating the Water Activity of Highly Concentrated Solutions of Sugars, Polyols, and Polyethylene Glycols

2008 ◽  
Vol 3 (1) ◽  
pp. 87-92 ◽  
Author(s):  
Rosa Baeza ◽  
Adriana Pérez ◽  
Virginia Sánchez ◽  
María C. Zamora ◽  
Jorge Chirife
Keyword(s):  
Water Activity ◽  
Polyethylene Glycols ◽  
Concentrated Solutions

Obtaining and Characterisation of Starch-Based Edible Films Incorporating Honey, Propolis and Bee Bread

2019 ◽  
Vol 23 (2) ◽  
pp. 193-198
Author(s):  
Monica Mironescu ◽  
Laura Fratila ◽  
Alexandru Hupert ◽  
Ion Dan Mironescu
Keyword(s):  
Water Activity ◽  
Mechanical Characteristics ◽  
Edible Films ◽  
Ash Content ◽  
Colour Intensity ◽  
Sensorial Analysis ◽  
Physical Chemical ◽  
Control Film ◽  
Bee Bread

Abstract This research investigates the physical-chemical, sensorial and mechanical characteristics of starch-based edible films incorporating three types of bee hive products: honey, propolis and bee bread, in concentrations varying from 1% to 3%, reported to starch. The results indicates an increasing of films moisture, water activity, ash content and acidity, in the order: honey<propolis<bee bread, all values increasing with the increasing of hive products percentage into the control film; aw is remaining at very low values, under 0.4. Sensorial analysis indicated honey as the better suited for improving taste and flavour and bee bread for increasing colour intensity of the films; the sensorial characteristics are maintained during 30 days of films storage, in all cases. Compared with the control starch-based film (which is elastic, brittle and hard), the films containing 2% bee hive products are elasto-plastic and more resistant to penetration, the resistance increasing in the order: bee bread<propolis<honey.

Molecular Transformations in DNA under the Influence of UV-radiation

2020 ◽  
Vol 04 ◽  
Author(s):  
Vigen G. Barkhudaryan ◽  
Gayane V. Ananyan ◽  
Nelli H. Karapetyan
Keyword(s):  
Uv Radiation ◽  
Uv Irradiation ◽  
Absorption Spectroscopy ◽  
Calf Thymus Dna ◽  
Dilute Solutions ◽  
Concentrated Solutions ◽  
Buffer Solution ◽  
Low Concentration ◽  
Calf Thymus ◽  
Dna Solutions

Background: The processes of destruction and crosslinking of macromolecules occur simultaneously under the influence of ultraviolet (UV) radiation in synthetic polymers, dry DNA and their concentrated solutions. Objective: The effect of UV radiation on calf thymus DNA in dilute solutions subjected to UV- irradiation was studied in this work. Method: The calf thymus DNA was studied in dilute solutions using viscometry, absorption spectroscopy and electrophoresis. Results: It was shown, that at a low concentration of DNA in the buffer solution ([DNA] = 85 μg / ml) under the influence of UV radiation, the processes of destruction of macromolecules and an increase in their flexibility predominate, which is accompanied by a gradual decrease in the viscosity of their solution. In addition, due to the low concentration of the solution, intramolecular crosslinking of macromolecules predominates, which also reduces their size and, consequently, the viscosity of the solution. Conclusion: It was concluded, that in dilute DNA solutions, due to the predominance of the processes of intramolecular crosslinking of macromolecules over intermolecular, only constant processes of decreasing the sizes of DNA macromolecules occur. As a result, its solubility remains virtually unchanged during UV irradiation. The described comments are also excellently confirmed by the results of absorption spectroscopy and electrophoresis

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